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<head><meta charset="utf-8"><title>Reporting Warnings on Compile? · t-compiler · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/index.html">t-compiler</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html">Reporting Warnings on Compile?</a></h3>

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<a name="226769027"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/226769027" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Grommish <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#226769027">(Feb 18 2021 at 06:04)</a>:</h4>
<p>I am compiling Rust several times a day at this point, is there a desire/place to report Warnings that I get (since I have to see them)?  Is it something the devs worry about?  I know WARNINGS are not errors, but I'm not sure how sanitized the rust code wants to be.  And yes, I know it's 1.49.0, but I'm just testing a known build before I switch over to 1.50.  The question still applies :)</p>
<p>example:</p>
<div class="codehilite"><pre><span></span><code>[1025/2614] Building CXX object lib/MC/CMakeFiles/LLVMMC.dir/XCOFFObjectWriter.cpp.o
In file included from /usr/include/string.h:495,
                 from /usr/include/c++/9/cstring:42,
                 from /home/grommish/openwrt/build_dir/hostpkg/rust-1.49.0/src/llvm-project/llvm/include/llvm/ADT/Hashing.h:53,
                 from /home/grommish/openwrt/build_dir/hostpkg/rust-1.49.0/src/llvm-project/llvm/include/llvm/ADT/ArrayRef.h:12,
                 from /home/grommish/openwrt/build_dir/hostpkg/rust-1.49.0/src/llvm-project/llvm/include/llvm/MC/MCAsmBackend.h:12,
                 from /home/grommish/openwrt/build_dir/hostpkg/rust-1.49.0/src/llvm-project/llvm/lib/MC/XCOFFObjectWriter.cpp:14:
In function &#39;char* strncpy(char*, const char*, size_t)&#39;,
    inlined from &#39;{anonymous}::Section::Section(const char*, llvm::XCOFF::SectionTypeFlags, bool, {anonymous}::CsectGroups)&#39; at /home/grommish/openwrt/build_dir/hostpkg/rust-1.49.0/src/llvm-project/llvm/lib/MC/XCOFFObjectWriter.cpp:146:12:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:34: warning: &#39;char* __builtin_strncpy(char*, const char*, long unsigned int)&#39; specified bound 8 equals destination size [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
</code></pre></div>



<a name="226769314"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/226769314" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#226769314">(Feb 18 2021 at 06:09)</a>:</h4>
<p>These are warnings from llvm, not rustc</p>



<a name="226769387"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/226769387" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#226769387">(Feb 18 2021 at 06:10)</a>:</h4>
<p>But yeah it might be useful to report them upstream</p>



<a name="226769413"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/226769413" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Grommish <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#226769413">(Feb 18 2021 at 06:10)</a>:</h4>
<p>OpenWrt screams about a lot by default, so I wanted to ask :)</p>



<a name="227054374"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/227054374" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Esteban Küber <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#227054374">(Feb 20 2021 at 01:20)</a>:</h4>
<p>Building <code>rustc</code> itself shouldn't have _any_ warnings in master (I'm pretty sure we deny them in CI, although that might have changed at some point). For warnings coming from LLVM, we might want to be aware of them, but I don't know how actionable they would be nor who would be looking at them, sadly. Filing tickets to LLVM directly _may_ be worthwhile, but I don't know what _their_ attitude towards those kind of reports is.</p>



<a name="227130666"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/227130666" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#227130666">(Feb 21 2021 at 00:47)</a>:</h4>
<blockquote>
<p>(I'm pretty sure we deny them in CI, although that might have changed at some point)</p>
</blockquote>
<p>In my experience we deny them locally too.</p>



<a name="227131140"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/227131140" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#227131140">(Feb 21 2021 at 00:57)</a>:</h4>
<p>There's an option (deny-warnings) which you can set to false in config.toml, or pass --warnings=warn and/or --warnings=deny on CLI to override config</p>



<a name="227131141"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/227131141" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#227131141">(Feb 21 2021 at 00:57)</a>:</h4>
<p>LLVM warnings we don't really do anything with ourselves I think</p>



<a name="227131155"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/131828-t-compiler/topic/Reporting%20Warnings%20on%20Compile%3F/near/227131155" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/131828-t-compiler/topic/Reporting.20Warnings.20on.20Compile.3F.html#227131155">(Feb 21 2021 at 00:58)</a>:</h4>
<p>(I would sort of guess that whatever LLVM's defaults are we also use)</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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